Beam switching and recovery

ABSTRACT

Apparatuses and methods of beam switching are presented. A beam switch message (BSM) is transmitted to a second device via a first beam set. The BSM includes a command to switch from communication via the first beam set to communication via a second beam set at a switch time. It is determined whether a response message is received from the second device via the first beam set, the response message indicating that the second device received the BSM. A communication is sent to the second device via the second beam set after the switch time when the response message is unreceived.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/396,082, entitled “FAST BEAM RECOVERY” and filed on Sep. 16,2016, the benefit of U.S. Provisional Application Ser. No. 62/401,814,entitled “BEAM SWITCH MESSAGE” and filed on Sep. 29, 2016, the benefitof U.S. Provisional Application Ser. No. 62/504,412, entitled “BEAMSWITCHING AND RECOVERY” and filed on May 10, 2017, and the benefit ofU.S. Provisional Application Ser. No. 62/504,428, entitled “BEAMSWITCHING WITH RESET STATES” and filed on May 10, 2017, each of which isexpressly incorporated by reference herein in its entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to apparatuses and methods for beam switching inwireless communication.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. Some aspects of 5G NR may be based on the 4G Long TermEvolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

For example, some wireless communications may utilize different beampairs from different antenna subarrays at a base station and at a userequipment (UE). The wireless communication may include transmitting andreceiving control and data signals. An efficient scheme for the basestation and/or the UE to switch beam pairs for wireless communicationmay improve the overall performance of the wireless communications.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Beamforming can be used to create a narrow beam pattern between, forexample, a base station (e.g., gNB) and a user equipment (e.g., a cellphone) that may enhance link budget and/or signal-to-noise ratio (SNR).Beamforming can offer several benefits, particularly for technologiesthat can suffer from high path loss, such as millimeter wave (mmW)communication. New techniques such as hybrid beamforming (analog anddigital), which are not present in 3G and 4G systems, may be used tofurther enhance some benefits. In single-beam implementations,beamforming can be used to create a single beam. In multi-beamimplementations, multiple beams can be created and used to cover a widerarea.

In multi-beam wireless communication (or simply, multi-beamcommunication), devices communicating via a beam pair may switch to adifferent beam pair for various reasons. For example, a base station anda UE communicating via a first beam pair may switch to a second beampair because the UE is moving out of the coverage area of the first beampair and into the coverage area of the second beam pair. The conditionand environment may change such that communication via a different beampair between the base station and the UE would be more advantageous.However, to be effective, beam switching requires a coordinated effortbetween the base station and the UE. In some situations, the beamswitching may not be so easily confirmed or synchronized.

Apparatuses and methods for beam switching are presented below. Theideas described below may, for example, increase the efficiency of beamswitching in various implementations by providing an enhanced form ofmessaging, may allow faster beam recovery when devices fail to switchbeams properly, etc.

In various embodiments, a first device can transmit a beam switchmessage (BSM) to a second device via a first beam set. The BSM caninclude a command to switch from communication via the first beam set tocommunication via a second beam set at a switch time. The first devicecan determine whether a response message is received from the seconddevice via the first beam set, the response message indicating that thesecond device received the BSM. The first device can send, to the seconddevice, a communication via the second beam set after the switch timewhen the response message is unreceived. The sent communication can be,for example, data, control information, or reference signals.

In some cases, the first device can also determine whether a secondresponse message is received from the second device in response to thesent communication and can maintain the second beam set forcommunication with the second device upon determining that the secondresponse message is received. In some cases, the first device can alsosend, to the second device, a second communication via the first beamset upon determining that the second response message is unreceived andcan determine whether a third response message is received from thesecond device via the first beam set, the third response messageindicating that the second device received the second communication.

The response message can include, for example, a reference signalstrength indicator (RSSI), reference signal received power (RSRP),reference signal received quality (RSRQ), an SNR, a signal tointerference plus noise ratio (SINR), an acknowledgment (ACK), or ameasurement report.

In various embodiments, a first device can monitor for a BSM from asecond device via a first beam set. The BSM can include a command toswitch from communication via the first beam set to communication via asecond beam set at a switch time. The first device can send a responsemessage to the second device when the BSM is received. The first devicecan monitor for a second communication from the second device via thefirst beam set when the BSM is unreceived, the second communication viathe first beam set being monitored at a second time subsequent to afirst time in which a first communication is sent to the first devicevia the second beam set.

In some cases, when the BSM from the second device is unreceived, thefirst device can also receive the second communication from the seconddevice via the first beam set can send a second response message via thefirst beam set to the second device in response to receiving the secondcommunication. In some cases, the first device can also receive the BSMfrom the second device via the first beam set, switch to the second beamset from the first beam set, receive the first communication from thefirst device via the second beam set, and send a second response messageto the second device in response to receiving the first communication.

In various embodiments, a first device can transmit a beam switchmessage to a second device via a first beam set. The beam switch messagecan include a command to switch from communication via the first beamset to communication via a second beam set at a switch time. The firstdevice can monitor for a response message from the second device. Theresponse message can indicate the second device received the beam switchmessage. The first device can determine whether the response message wasreceived from the second device. The first device can switch tocommunication via the second beam set at the switch time whether or notthe response message was received. For example, switching beam setswhether or not a response message was received may avoid atime-consuming recovery process, particularly if the second devicereceived the beam switch message and switched beam sets.

In various embodiments, a first device can transmit a beam switchmessage to a second device via a first beam set and can monitor for aresponse message from the second device. The first device can determinewhether the response message was received from the second device, andcan switch to communication via the second beam set at the switch timeif the response message was received. The first device can determine aswitch decision if the response message was not received. The switchdecision can be either to continue communication via the first beam setat the switch time or to switch to communication via the second beam setat the switch time. The first device can communicate via the first beamset or the second beam set based on the switch decision. For example, ifthe first device determines that delivery failure of the beam switchmessage is more likely than delivery failure of the response message,then the second device is more likely to have remained on the first beamset at the switch time. Therefore, the first device may choose not toswitch beam sets at the switch time.

In various embodiments, a first device can transmit a beam switchmessage to a second device via a first beam set and can switch tocommunication via the second beam set at the switch time withoutmonitoring prior to the switch time for a response message indicatingthe second device received the beam switch message. The first device candetermine after the switch time if the second device is communicatingvia the second beam set. In this way, for example, signaling may bereduced because a response process need not be performed. This approachmay work well, particularly when the possibility of delivery failure ofthe beam switch message is low.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a DLframe structure, DL channels within the DL frame structure, an UL framestructure, and UL channels within the UL frame structure, respectively.

FIG. 3 is a diagram illustrating an example of a base station and UE inan access network.

FIG. 4 is a diagram illustrating a base station in communication with aUE.

FIG. 5 includes diagrams of communications between a base station and aUE via multiple beams.

FIG. 6 illustrates an example of single-switch beam switch messagesaccording to various embodiments.

FIG. 7 illustrates an example of multiple-switch BSMs according tovarious embodiments.

FIG. 8 illustrates an example situation of signal error in multi-beamwireless communication.

FIG. 9 illustrates another example situation of signal error inmulti-beam wireless communication.

FIGS. 10A-C illustrate an example implementation of a method of wirelesscommunication in accordance with various embodiments.

FIGS. 11A-C illustrates an example implementation of a method ofwireless communication in accordance with various embodiments.

FIG. 12A-B illustrate an example implementation of a method of wirelesscommunication in accordance with various embodiments.

FIGS. 13A-B illustrate another example implementation of a method ofwireless communication in accordance with various embodiments.

FIG. 14 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments.

FIG. 15 illustrates an implementation of FIG. 14 in a situation that aresponse to a BSM is lost.

FIG. 16 illustrates an implementation of FIG. 14 in a situation that aBSM is lost.

FIG. 17 illustrates another example implementation of a method ofwireless communication in accordance with various embodiments.

FIG. 18 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments.

FIG. 19 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments.

FIG. 20 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 21 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 22 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 23 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 24 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 25 is a flowchart illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.

FIG. 26 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 27 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 28 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 29 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 30 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 31 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 32 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 33 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 34 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 35 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 36 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 37 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well-known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, and an Evolved Packet Core (EPC) 160. The basestations 102 may include macro cells (high power cellular base station)and/or small cells (low power cellular base station). The macro cellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 (collectively referred to as Evolved UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)) interface with the EPC 160 through backhaul links 132 (e.g.,S1 interface). In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160) with eachother over backhaul links 134 (e.g., X2 interface). The backhaul links134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) bandwidthper carrier allocated in a carrier aggregation of up to a total of YxMHz (x component carriers) used for transmission in each direction. Thecarriers may or may not be adjacent to each other. Allocation ofcarriers may be asymmetric with respect to DL and UL (e.g., more or lesscarriers may be allocated for DL than for UL). The component carriersmay include a primary component carrier and one or more secondarycomponent carriers. A primary component carrier may be referred to as aprimary cell (PCell) and a secondary component carrier may be referredto as a secondary cell (SCell).

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

The gNodeB (gNB) 180 may operate in millimeter wave (mmW) frequenciesand/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 184 withthe UE 104 to compensate for the extremely high path loss and shortrange. The base station 180 may wirelessly communicate with UE 182 viamultiple beams (not shown). The multiple beams of base station 180 mayprovide communication coverage for the geographic coverage area of basestation 180, such that the geographic coverage area may include multiplebeams emanating from base station 180. Communication link 184 betweenbase station 180 and UE 182 can be established via a beam set (forexample, a beam pair) and may include UL (also referred to as reverselink) transmissions from the UE to the base station and/or DL (alsoreferred to as forward link) transmissions from the base station to theUE. Communication link 184 may be established by beamforming based on,for example, MIMO antenna technology, and may also include spatialmultiplexing, and/or transmit diversity.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService (PSS), and/or other IP services. The BM-SC 170 may providefunctions for MBMS user service provisioning and delivery. The BM-SC 170may serve as an entry point for content provider MBMS transmission, maybe used to authorize and initiate MBMS Bearer Services within a publicland mobile network (PLMN), and may be used to schedule MBMStransmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The base station may also be referred to as a gNB, Node B, eNB, anaccess point, a base transceiver station, a radio base station, a radiotransceiver, a transceiver function, a basic service set (BSS), anextended service set (ESS), or some other suitable terminology. The basestation 102 provides an access point to the EPC 160 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a toaster, or any other similarfunctioning device. Some of the UEs 104 may be referred to as IoTdevices (e.g., parking meter, gas pump, toaster, vehicles, etc.). The UE104 may also be referred to as a station, a mobile station, a subscriberstation, a mobile unit, a subscriber unit, a wireless unit, a remoteunit, a mobile device, a wireless device, a wireless communicationsdevice, a remote device, a mobile subscriber station, an accessterminal, a mobile terminal, a wireless terminal, a remote terminal, ahandset, a user agent, a mobile client, a client, or some other suitableterminology.

Referring again to FIG. 1, in certain aspects, UE 182 and/or basestation 180 may be configured to perform beam recovery by, for example,sending a BSM, determining whether a response is received, andcommunicating via a target beam when a response to the BSM isunreceived, and performing a beam switch reset by, for example, sendinga first BSM, selecting a reset state, and sending a second BSMindicating the reset state (198).

FIG. 2A is a diagram 200 illustrating an example of a DL framestructure. FIG. 2B is a diagram 230 illustrating an example of channelswithin the DL frame structure. FIG. 2C is a diagram 250 illustrating anexample of an UL frame structure. FIG. 2D is a diagram 280 illustratingan example of channels within the UL frame structure. Other wirelesscommunication technologies may have a different frame structure and/ordifferent channels. A frame (10 ms) may be divided into 10 equally sizedsubframes. Each subframe may include two consecutive time slots. Aresource grid may be used to represent the two time slots, each timeslot including one or more time concurrent resource blocks (RBs) (alsoreferred to as physical RBs (PRBs)). The resource grid is divided intomultiple resource elements (REs). For a normal cyclic prefix, an RBcontains 12 consecutive subcarriers in the frequency domain and 7consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) inthe time domain, for a total of 84 REs. For an extended cyclic prefix,an RB contains 12 consecutive subcarriers in the frequency domain and 6consecutive symbols in the time domain, for a total of 72 REs. Thenumber of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry DL reference (pilot)signals (DL-RS) for channel estimation at the UE. The DL-RS may includecell-specific reference signals (CRS) (also sometimes called common RS),UE-specific reference signals (UE-RS), and channel state informationreference signals (CSI-RS). FIG. 2A illustrates CRS for antenna ports 0,1, 2, and 3 (indicated as R₀, R₁, R₂, and R₃, respectively), UE-RS forantenna port 5 (indicated as R₅), and CSI-RS for antenna port 15(indicated as R). FIG. 2B illustrates an example of various channelswithin a DL subframe of a frame. The physical control format indicatorchannel (PCFICH) is within symbol 0 of slot 0, and carries a controlformat indicator (CFI) that indicates whether the physical downlinkcontrol channel (PDCCH) occupies 1, 2, or 3 symbols (FIG. 2B illustratesa PDCCH that occupies 3 symbols). The PDCCH carries downlink controlinformation (DCI) within one or more control channel elements (CCEs),each CCE including nine RE groups (REGs), each REG including fourconsecutive REs in an OFDM symbol. A UE may be configured with aUE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCHmay have 2, 4, or 8 RB pairs (FIG. 2B shows two RB pairs, each subsetincluding one RB pair). The physical hybrid automatic repeat request(ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0and carries the HARQ indicator (HI) that indicates HARQ ACK/negative ACK(NACK) feedback based on the physical uplink shared channel (PUSCH). Theprimary synchronization channel (PSCH) may be within symbol 6 of slot 0within subframes 0 and 5 of a frame. The PSCH carries a primarysynchronization signal (PSS) that is used by a UE to determinesubframe/symbol timing and a physical layer identity. The secondarysynchronization channel (SSCH) may be within symbol 5 of slot 0 withinsubframes 0 and 5 of a frame. The SSCH carries a secondarysynchronization signal (SSS) that is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DL-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSCH and SSCH to form a synchronization signal (SS) block. The MIBprovides a number of RBs in the DL system bandwidth, a PHICHconfiguration, and a system frame number (SFN). The physical downlinkshared channel (PDSCH) carries user data, broadcast system informationnot transmitted through the PBCH such as system information blocks(SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry demodulation referencesignals (DM-RS) for channel estimation at the base station. The UE mayadditionally transmit sounding reference signals (SRS) in the lastsymbol of a subframe. The SRS may have a comb structure, and a UE maytransmit SRS on one of the combs. The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL. FIG. 2D illustrates an example of various channels within anUL subframe of a frame. A physical random access channel (PRACH) may bewithin one or more subframes within a frame based on the PRACHconfiguration. The PRACH may include six consecutive RB pairs within asubframe. The PRACH allows the UE to perform initial system access andachieve UL synchronization. A physical uplink control channel (PUCCH)may be located on edges of the UL system bandwidth. The PUCCH carriesuplink control information (UCI), such as scheduling requests, a channelquality indicator (CQI), a precoding matrix indicator (PMI), a rankindicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, andmay additionally be used to carry a buffer status report (BSR), a powerheadroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a packet dataconvergence protocol (PDCP) layer, a radio link control (RLC) layer, anda medium access control (MAC) layer. The controller/processor 375provides RRC layer functionality associated with broadcasting of systeminformation (e.g., MIB, SIBs), RRC connection control (e.g., RRCconnection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter radio access technology(RAT) mobility, and measurement configuration for UE measurementreporting; PDCP layer functionality associated with headercompression/decompression, security (ciphering, deciphering, integrityprotection, integrity verification), and handover support functions; RLClayer functionality associated with the transfer of upper layer packetdata units (PDUs), error correction through ARQ, concatenation,segmentation, and reassembly of RLC service data units (SDUs),re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto transport blocks(TBs), demultiplexing of MAC SDUs from TBs, scheduling informationreporting, error correction through HARQ, priority handling, and logicalchannel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the RXprocessor 356. The TX processor 368 and the RX processor 356 implementlayer 1 functionality associated with various signal processingfunctions. The RX processor 356 may perform spatial processing on theinformation to recover any spatial streams destined for the UE 350. Ifmultiple spatial streams are destined for the UE 350, they may becombined by the RX processor 356 into a single OFDM symbol stream. TheRX processor 356 then converts the OFDM symbol stream from thetime-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Base station 310 may wirelessly communicate with UE 350 via multiplebeams (not shown). For example, TX processor 316 of base station 310 maycontrol antennas 320 to form a beam directed at UE 350, and RX processor356 of UE 350 may control antennas 352 to receive communication via abeam directed at base station 310. In other words, a communication linkbetween base station 310 and UE 350 can be established via a beam set(for example, a beam pair), which may include UL transmissions from theUE to the base station and/or DL transmissions from the base station tothe UE.

FIG. 4 is a diagram 400 illustrating multi-beam communication in which abase station 402 is in communication with a UE 404. Referring to FIG. 4,when the UE 404 turns on, the UE 404 searches for a nearby NR network.The UE 404 discovers the base station 402, which belongs to an NRnetwork. The base station 402 transmits an SS block including the PSS,SSS, and the PBCH (including the MIB) periodically in different transmitdirections 402 a-402 h. The UE 404 receives a transmission in transmitdirection 402 e, including the PSS, SSS, and PBCH. Based on the receivedSS block, the UE 404 synchronizes to the NR network and camps on a cellassociated with the base station 402.

FIG. 5 includes diagrams of communications between a base station and aUE via multiple beams. In some examples, diagrams 560 and 561 depict mmWcommunications between base station 562 and UE 566. The diagram 560depicts the case where base station 562 (e.g., an example of a basestation) transmits to UE 566 via at least one of beam sets 510 and 512,which may be referred to simply as beams 510 and 512. The beams 510/512may carry the DL/UL signals discussed in the previous sections. Thediagram 561 depicts the case where UE 566 transmits to base station 562via at least one of beams 520 and 522. The beams 520/522 may carry theDL/UL signals discussed in the previous sections. For example, beam 510of first beam pair 550 and beam 512 of second beam pair 552 carry the DLsignals. The beam 520 of first beam pair 550 and beam 522 of second beam552 carry the UL signals.

Each of beams 510, 512, 520, and 522 may include more than one beam. Inthis regard, a beam set may include one or more beams. For example, beam510 may include a beam 510_C to carry control signals and channels and abeam 510_D to carry data signals and channels. In some examples, thebeams may be associated. For example, in one case, base station 562 andUE 566 may communicate via beam 510 and beam 520. That is, base station562 may transmit to UE 566 via beam 510 and receive from UE 566 via beam520. The beams 510 and 520 are thus associated and may be referred to asa beam pair. For example, beam 510 and associated beam 520 may bereferred to as first beam pair 550, and beam 512 and associated beam 522may be referred to as second beam pair 552.

The base station (e.g., a gNB) 562 and UE 566 may communicate overactive beam pairs (e.g., first beam pair 550 and or second beam pair552). Active beam pairs may be base station 562 and UE 566 beam pairsthat carry data and control channels such as PDSCH, PDCCH, PUSCH, andPUCCH. In one aspect, base station 562 may monitor active beam pairsusing reported measurements of signals (e.g., reported by UE 566 by thebeams from the base station (e.g., the base station can monitor thebeams from the UE by measuring such beams directly)) such as measurementreference signal (MRS), CSI-RS, primary synchronization signal andSecondary synchronization signal (SYNC). To do so, base station 562 maysend a measurement request, for example, a beam state informationrequest to UE 566. UE 566 may, in response, measure the measurementsignals and send a report that contains beam identifications and beamquality for each beam measured. Base station 562 may then signal a beamswitch to the UE. The beam switch signal (e.g., message) may contain thetarget beam identifier (e.g., identify the target beam pair) and/or timeto switch base station 562 and UE 566 beam pairs. The time may beindicated in terms of, for example, subframes, slots, or mini-slots(e.g., specifying a subframe, slot, or mini-slot identifier or anoffset). In some examples, base station 562 may signal to switch thebeam pairs without explicit beam identifiers. For example, the beamswitch may be based on an agreement prior to the transmission of thesignal to switch the beam pairs. At such a time, both base station 562and UE 566 can switch beam pairs (e.g., switch from a source first beampair 550 to target second beam pair 552).

UE 566 may transmit to base station 562 a response message for the beamswitch. In some examples, UE 566 may signal the beam switch, and basestation 562 may transmit the response message as described above. Wherethe embodiment provided relates to base station 562 initiating the beamswitch (and UE 566 confirms the beam switch), it is understood theexample likewise applies to the example in which UE 566 initiates thebeam switch (and base station 562 confirms the beam switch).

FIG. 6 illustrates an example of single-switch beam switch messagesaccording to various embodiments. In FIG. 6, a base station 601 iscommunicating with a UE 603 via a first beam set 605 at subframe 0. Thebase station 601 and UE 603 may be, for example, base station 562 and UE566, respectively, in FIG. 5 above. At subframe 1, base station 601transmits a BSM 607 to UE 603 via first beam set 605. The BSM 607includes an instruction for UE 603 to switch from communication viafirst beam set 605 to communication via a second beam set 609 at aswitch time 611. The BSM 607 is an example of a single-switch BSMbecause BSM 607 instructs UE 603 to perform only one beam switch. Inthis example, base station 601 expects to receive a response message,e.g., an ACK, from the UE at an expected ACK time 613, and therefore,the base station is monitoring for the response message. In variousembodiments of the current example and other examples presented herein,a response message may be any indication that a BSM or other signal hasbeen received. For example, a response message may be an ACK, a ReceivedSignal Strength Indicator (RSSI), a SNR, a measurement report, etc.,that is in response to a BSM or other signal. Monitoring for a responsemessage may be done actively or passively. For example, a base stationmay take active measures to monitor, such as tuning to a particularfrequency or channel on which the response message is expected. On theother hand, a base station may monitor passively by, for example, merelyexpecting to receive a response message in the normal course ofoperation.

UE 603 receives BSM 607 and transmits an ACK 615 for base station 601 toreceive at expected ACK time 613. The base station 601 receives ACK 615at expected ACK time 613, and as a result, base station 601 knows thatUE 603 will perform the beam switch. At switch time 611, base station601 and UE 603 perform a beam switch 617 from first beam set 605 tosecond beam set 609.

At subframe 9, base station 601 may decide to switch beams again and cantransmit a BSM 619 to UE 603 via second beam set 609. The BSM 619includes an instruction for UE 603 to switch from communication viasecond beam set 609 to communication via a third beam set 621 at aswitch time 623. BSM 619 is another example of a single-switch BSMbecause BSM 619 instructs UE 603 to perform only one beam switch. Thebase station 601 monitors for an ACK at expected ACK time 625. UE 603receives BSM 619 and transmits an ACK 627 for base station 601 toreceive at expected ACK time 625. The base station 601 receives ACK 627at expected ACK time 625, and as a result, base station 601 knows thatUE 603 will perform the beam switch. At switch time 623, base station601 and UE 603 perform a beam switch 629 from second beam set 609 tothird beam set 621. Thus, in the example of FIG. 6, BSM 607 and BSM 619are examples of single-switch BSMs.

FIG. 7 illustrates an example of multiple-switch BSMs according tovarious embodiments. In FIG. 7, a base station 701 is communicating witha UE 703 via a first beam set 705 at subframe 0. At subframe 1, basestation 701 transmits a BSM 707 to UE 703 via first beam set 705. TheBSM 707 includes an instruction for UE 703 to switch from communicationvia first beam set 705 to communication via a second beam set 709 at afirst switch time 711, and to switch from communication via second beamset 709 to communication via a third beam set 721 at a second switchtime 723. The BSM 707 is an example of a multiple-switch BSM because BSM707 instructs UE 703 to perform multiple beam switches. In this example,base station 701 expects to receive a response message, e.g., an ACK,from the UE at an expected ACK time 713, and therefore, the base stationis monitoring for the response message.

UE 703 receives BSM 707 and transmits an ACK 715 for base station 701 toreceive at expected ACK time 713. The base station 701 receives ACK 715at expected ACK time 713, and as a result, base station 701 knows thatUE 703 will perform the beam switches. At first switch time 711, basestation 701 and UE 703 perform a beam switch 717 from first beam set 705to second beam set 709. At second switch time 723, base station 701 andUE 703 perform a beam switch 729 from second beam set 709 to third beamset 721. Thus, BSM 707 is an example of a multiple-switch BSM becauseBSM 707 includes instructions to perform multiple beam switches.

In various embodiments, multiple-switch BSMs may be useful. For example,as a comparison of FIGS. 6 and 7 shows, using a multiple-switch BSM tosignal multiple beam switches can reduce the amount of signaling byeliminating the need for additional BSMs and ACKs for each beam switchafter the first beam switch. Also, by reducing the number of BSMs andACKs required for multiple beam switches, a multi-switch BSM can reducethe number of instances in which signal failure can occur. Therefore,systems that use multi-switch BSMs may be less susceptible to theeffects of signal failure.

Multiple-switch BSMs can be used, for example, when multiple beamswitches can be determined prior to transmission of a BSM. For example,in communication systems in which a UE moves through the coverage areasof multiple beam sets in a predictable way, a base station may be ableto predict at one time the multiple beam switches will be necessary tostay in communication with the UE. For example, a base station may servea rail line on which trains travel at a known speed through multiplebeam sets of the base station. The base station may know, for example,when a UE traveling on a southbound train reaches the coverage area ofthe base station, the UE will establish a connection with a first beamset of the base station. The base station may also know that it takesthe southbound train a first amount of time to pass through the firstbeam set and reach a second beam set, and a second amount of time topass through the second beam set and reach a third beam set, and so on.Therefore, when the base station determines a new UE has established aconnection via the first beam set, the base station may predict that afirst beam switch from the first beam set to the second beam set shouldoccur after the first amount of time and that a second beam switch fromthe second beam set to the third beam set should occur after the secondamount of time after the first beam switch. Thus, the base station maysend a multi-switch BSM to each southbound UEs, for example, immediatelyafter the connection with the first beam set is established. In thisway, for example, the base station may be able to reduce significantlythe number of BSMs and corresponding ACKs, along with the potentialsignal errors associated with the multiple BSMs and ACKs.

However, regardless of whether single-switch or multi-switch BSMs areused, signal error can occur. In some examples, a base station does notreceive an expected response message from the UE in a timely fashion.

FIG. 8 illustrates an example situation of signal error in multi-beamwireless communication. In this example, a base station 801 and a UE 803are communicating via a first beam set 805, and base station 801transmits a BSM 807 instructing UE 803 to switch beams at a switch time809. However, UE 803 does not receive BSM 807. Because UE 803 does notreceive BSM 807, UE 803 does not transmit an ACK, and base station 801does not receive an ACK at an expected ACK time 811. The base station801 does not know whether UE 803 will switch beams at switch time 809because the base station 801 does not know whether the UE 803 failed toreceive the BSM 807 or the UE 803 received the BSM 807 and sent an ACKthat was not received by the base station 801. In this case, UE 803 willnot switch beam sets at switch time 809, but will continue communicatingvia first beam set 805.

FIG. 9 illustrates another example situation of signal error inmulti-beam wireless communication. In this example, a base station 901and a UE 903 are communicating via a first beam set 905, and basestation 901 transmits a BSM 907 instructing UE 903 to switch beams to asecond beam set 908 at a switch time 909. In this example, UE 903receives BSM 907 and transmits an ACK 910. However, base station 901does not receive ACK 910 at an expected ACK time 911. As in the exampleof FIG. 8, base station 901 does not know whether UE 903 will switchbeams at switch time 909 because the base station 901 does not knowwhether the UE 903 failed to receive the BSM 907 or the UE 903 receivedthe BSM 907 and sent an ACK that was not received by the base station901. In this case, UE 903 does perform a beam switch 913 to switch tocommunication via second beam set 908 at switch time 909.

Both scenarios described with respect to FIGS. 8 and 9 result in thebase station not receiving the response message (e.g., an ACK from theUE), and hence the base station may not know if the UE will switch tothe target beam set. If the base station switches to the target beam setat the switch time, but the UE does not switch, beam misalignment mayresult (e.g., the transmitting apparatus and the receiving apparatuscommunicating via different beam pairs). Likewise, if the UE switches tothe target beam set at the switch time, but the base station does notswitch, beam misalignment may result.

It is noted that some implementations of various embodiments describedherein may help avoid or help mitigate the affects of beam misalignmentdue to, for example, signaling errors such as BSM or ACK deliveryfailure as described above. In particular, FIGS. 11 and 12 illustrateexample beam switch methods that may be implemented before a switchtime. FIGS. 14-18 illustrate example beam switch methods that may beimplemented after a switch time. FIG. 19 illustrates an example beamswitch method that may be implemented to avoid BSM and ACK signalingerrors altogether.

Turning first to FIGS. 10-13, these figures describe various examples ofsystems and methods in which a beam switch message can indicate a beamreset state, which may provide advantages to beam switching inmulti-beam systems. FIG. 10 illustrates two reset states in which a BSMcan either indicate to continue execution of a previous beam switchinstruction or can indicate to disregard the previous beam switchinstruction. FIGS. 11 and 12 illustrate two example ways in which a BSMindicating a reset state may help avoid a time-consuming beam recoveryprocedure and mitigate instances of beam misalignment. FIG. 13illustrates an example use of beam reset states in a multiple-switchBSM, such as described above with respect to FIG. 7.

FIGS. 10A-C illustrate an example implementation of a method of wirelesscommunication in accordance with various embodiments. FIG. 10A shows thestate of communication between a base station 1001 and a UE 1003 at afirst time. FIG. 10B shows the state of communication between basestation 1001 and UE 1003 at a later time in the case that a first resetstate is selected. FIG. 10C shows the state of communication betweenbase station 1001 and UE 1003 at the later time in the case that asecond reset state is selected. Turning first to FIG. 10A, base station1001 can transmit a BSM 1005 including a first instruction for switchingbeams to UE 1003, which can establish a planned beam switch 1007. Forexample, base station 1001 and UE 1003 may be communicating via a firstbeam set, and BSM 1005 instructs UE 1003 to switch to a second beam set.The UE 1003 receives BSM 1005 and transmits an ACK 1009, and basestation receives ACK 1009.

The base station 1001 decides to transmit a second BSM to UE 1003, andthe base station 1001 selects a reset state to be indicated by thesecond BSM. FIG. 10B and FIG. 10C illustrate communication resultingfrom selection of, respectively, a first reset state and a second resetstate.

FIG. 10B illustrates communication based on a first reset state, inwhich UE 1003 disregards the first instruction sent in BSM 1005. Thebase station 1001 transmits a BSM 1011 to UE 1003. BSM 1011 includes asecond instruction for switching beams, which can establish a new beamswitch 1013, and indicates the selected reset state in which UE 1003disregards the first instruction. The UE 1003 receives BSM 1011 andtransmits an ACK 1015, and base station receives ACK 1015. In thisexample, UE 1003 has not completed execution of the first instructionbecause UE 1003 has not executed planned beam switch 1007. Therefore, UE1003 disregards planned beam switch 1007, which is represented asdisregarded beam switch 1017 in FIG. 10, and executes only new beamswitch 1013.

On the other hand, FIG. 10C illustrates communication based on a secondreset state, in which UE 1003 maintains execution of the firstinstruction sent in BSM 1005, thus, UE 1003 augments the firstinstruction with a second instruction. The base station 1001 transmits aBSM 1019 to UE 1003. BSM 1019 includes a second instruction forswitching beams, which can establish an added beam switch 1021, andindicates the selected reset state in which UE 1003 maintains executionof the first instruction. The UE 1003 receives BSM 1019 and transmits anACK 1023, and base station receives ACK 1023. In this example, UE 1003has not completed execution of the first instruction because UE 1003 hasnot executed planned beam switch 1007. UE 1003 maintains execution ofthe first instruction by executing planned beam switch 1007, andaugments the first instruction with the second instruction by alsoexecuting added beam switch 1021.

In various embodiments, the second BSM can indicate which of the resetstates was selected by setting a bit to 0 or 1, such as a flag. Forexample, a bit set to 0 may indicate maintaining execution of the firstinstruction, and the bit set to 1 may indicate disregarding the firstinstruction. In various embodiments, the second BSM may indicate one ofthe selected states by not providing an indicator. In other words, thesecond BSM may indicate one of the selected states by excludinginformation that one of the reset states was selected. For example, ifno indicator is provided, the UE may default to one of the reset states,such as defaulting to disregarding the first instruction. In someexamples, the reset state field may operate similarly to the new dataindicator or NDI bit for HARQ operation. In some examples, the resetstate information may be an empty field (e.g., the reset state indicatesa null flag or no reset state information is provided in the beam switchmessage).

FIGS. 11 and 12 will now be discussed. These figures illustrate variousembodiments that may be implemented before a switch time to help avoidpotential beam misalignment due to signal errors such as describedabove, thus helping to avoid potentially time-consuming beam recoveryprocedures.

FIGS. 11A-C illustrates an example implementation of a method ofwireless communication in accordance with various embodiments. FIG. 11Ashows the state of communication between a base station 1101 and a UE1103 at a first time, FIG. 11B shows the state of communication betweenbase station 1101 and UE 1103 at a second time later than the firsttime, and FIG. 11C shows the state of communication between base station1101 and UE 1103 at a third time later than the second time. Turningfirst to FIG. 11A, base station 1101 can transmit a BSM 1105 to UE 1103.For example, base station 1101 and UE 1103 may be communicating via afirst beam set, and BSM 1105 instructs UE 1103 to switch to a secondbeam set. Thus, BSM 1105 establishes a planned beam switch 1107. In thisexample, base station 1101 expects a response message from UE 1103 at anexpected ACK time 1109. The UE 1103 receives BSM 1105 and transmits anACK 1111. However, base station 1101 does not receive ACK 1111, andtherefore, the base station does not know whether UE 1103 will performplanned beam switch 1107.

Turning to FIG. 11B, because insufficient time exists between expectedACK time 1109 and planned beam switch 1107, base station 1101 transmitsa BSM 1113 to UE 1103 that establishes a new beam switch 1115 at a latertime than planned beam switch 1107. The UE 1103 receives BSM 1113, andbecause the default behavior of UE 1103 is to cancel execution of anyinstructions in previous BSMs if the UE receives a new BSM, planned beamswitch 1107 becomes disregarded beam switch 1117. The base station 1101monitors for a response message at an expected ACK time 1119. UE 1103transmits an ACK 1121. However, base station 1101 does not receive ACK1121, and therefore, the base station does not know whether UE 1103 willperform new beam switch 1115. However, because BSM 1113 instructed UE1103 to delay the beam switch, base station 1101 is able to transmitanother BSM and potentially receive a response message before new beamswitch 1115.

Turning to FIG. 11C, because insufficient time again exists before thebeam switch (i.e., new beam switch 1115), base station 1101 transmits aBSM 1123 to UE 1103 that establishes a new beam switch 1125 at a latertime than new beam switch 1115. The UE 1103 receives BSM 1123, and newbeam switch 1115 becomes disregarded beam switch 1127. The base station1101 monitors for a response message at an expected ACK time 1129. UE1103 transmits an ACK 1131. This time, base station 1101 receives ACK1131, and both base station 1101 and UE 1103 can switch beams accordingto new beam switch 1125. Thus, by delaying the planned beam switch, abase station and a UE may continue communication on a source beam setuntil a response is received. In contrast, if base station 1101 had notdelayed the planned beam switch, a time-consuming beam recovery processmay have been initiated at the time of planned beam switch 1107, forexample.

FIG. 12A-B illustrate an example wireless communication via multiplebeams according to various embodiments. In particular, FIG. 12A showsthe state of communication between a base station 1201 and a UE 1203 ata first time, and FIG. 12B shows the state of communication between basestation 1201 and UE 1203 at a later time. Turning first to FIG. 12A,base station 1201 can transmit a BSM 1205 to UE 1203. For example, basestation 1201 and UE 1203 may be communicating via a first beam set, andBSM 1205 instructs UE 1203 to switch to a second beam set. Thus, BSM1205 establishes a planned beam switch 1207. In this example, basestation 1201 expects a response message from UE 1203 at an expected ACKtime 1209. However base station 1201 does not receive a responsemessage, and therefore, the base station does not know whether UE 1203will perform planned beam switch 1207.

Turning to FIG. 12B, because sufficient time exists between expected ACKtime 1209 and planned beam switch 1207, base station 1201 transmitsanother BSM 1211 to UE 1203. BSM 1211 establishes a new beam switch1213. In this example, new beam switch 1213 is the same as planned beamswitch 1207, i.e., the same target beam set and the same switch time.The base station 1201 monitors for a response message at an expected ACKtime 1215. In this example, UE 1203 receives BSM 1205 and transmits anACK 1217, which is received by base station 1201. In this example, thedefault behavior of UE 1203 is to cancel execution of any instructionsin previous BSMs if the UE receives a new BSM. In this case, basestation 1201 and UE 1203 can both switch to the target beam set andcontinue communicating. This approach can work well if there issufficient time between the first BSM and the planned beam switchbecause the base station and UE can continue communication via thesource beam set. However, in some cases, the base station might not havesufficient time before a planned beam switch to communicate effectivelywith the UE.

FIGS. 13A-B illustrate another example implementation of a method ofwireless communication in accordance with various embodiments. Inparticular, FIGS. 13A-B illustrate an example use of reset states in animplementation with multiple-switch BSMs. FIG. 13A shows the state ofcommunication between a base station 1301 and a UE 1303 at a first time,and FIG. 13B shows the state of communication between base station 1301and UE 1303 at later time in the case that a first reset state isselected. Turning first to FIG. 13A, base station 1301 can transmit aBSM 1305 including a first instruction for switching beams to UE 1303.In this case, the first instruction includes multiple beam switches,such as BSM 707 described above with respect to FIG. 7. BSM 1305establishes two planned beam switches, i.e., planned beam switch 1307and planned beam switch 1308. For example, base station 1301 and UE 1303may be communicating via a first beam set, and BSM 1305 instructs UE1303 to switch to a second beam set for planned beam switch 1307 and toswitch to a third beam set for planned beam switch 1308. The UE 1303receives BSM 1305 and transmits an ACK 1309, and base station receivesACK 1309.

The base station 1301 decides to transmit a second BSM to UE 1303, andthe base station 1301 selects a reset state to be indicated by thesecond BSM. FIG. 13B illustrates the communication resulting fromselection of a reset state in which UE 1303 maintains execution of thefirst instruction. Unlike the example of FIG. 10C, base station 1301transmits the second BSM after UE 1303 has started execution of thefirst instruction for beam switching. However, the second BSM istransmitted before UE 1303 completes execution of the first instruction.

FIG. 13B illustrates communication based on a first reset state, inwhich UE 1303 maintains execution of the first instruction sent in BSM1305. The base station 1301 transmits a BSM 1311 to UE 1303 afterplanned beam switch 1307 has been completed. The completion of plannedbeam switch 1307 is illustrated in FIG. 13B by completed beam switch1312. BSM 1311 includes a second instruction for switching beams, whichcan establish an added beam switch 1313, and indicates the selectedreset state in which UE 1303 maintains execution of the firstinstruction. In this case, UE 1303 has not completed execution of thefirst instruction because the UE has not completed planned beam switch1308. The UE 1303 receives BSM 1305 and transmits an ACK 1315, and basestation receives ACK 1315. In this example, UE 1303 has not completedexecution of the first instruction because UE 1303 has not executedplanned beam switch 1308. Therefore, UE 1303 augments planned beamswitch 1308 with added beam switch 1313.

In various embodiments, the BSM 1311 could indicate a reset state inwhich UE 1303 disregards the first instruction, similar to the exampleof FIG. 10B. In this case, even though completed beam switch 1312 hasalready been executed, UE 1303 can disregard planned beam switch 1308.In other words, UE 1303 can disregard the unexecuted portion of thefirst instruction.

Now turning to FIGS. 14-18, these figures illustrate example beam switchmethods that may be implemented after a switch time to recover frompotential beam misalignment due to signal errors such as describedabove.

FIG. 14 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments. Initially, a basestation 1401 and a UE 1403 can be communicating via a first beam set1405 using, for example, mmW communications. The base station 1401 andUE 1403 may, for example, correspond to base station 562 and UE 566 inFIG. 5 above, and base station 1401 may transmit various DL signals andchannels to UE 1403 via first beam set 1405, such as beam or beams 510.UE 1403 may transmit various UL signals and channels to base station1401 via first beam set 1405, such as beam or beams 520 (which areassociated with beam or beams 510 in first beam pair 550, e.g., firstbeam set 1405).

The base station 1401 can transmit a BSM 1407 including an instructionto switch to communication via a second beam set 1409 at a switch time1411. The BSM 1407 may include information of a beam identifier forsecond beam set 1409, also referred to as the target beam, which couldbe, e.g., second beam pair 552. In some examples, BSM 1407 may notinclude a beam identifier. In some examples, BSM 1407 may be transmittedas part of a MAC or RRC message. The base station 1401 may expect aresponse message, e.g., an ACK, from UE 1403 at an expected ACK time1413 and, therefore, may be monitoring for a response indicating receiptof BSM 1407. UE 1403 may include the target beam (second beam set)identifiers in the UL transmission to echo back the target beamidentifiers. In one aspect, UE 1403 may generate a sequence from thetarget beam identifiers, and include the sequence in the ULtransmission. The base station 1401 may determine and confirm the targetbeam pair from the sequence in the UL transmission. In some examples,both the source beam pair (first beam set) and the target beam pair maybe of sufficient quality for communication, the mechanism may help basestation 1401 to determine which of the source beam pair and the targetbeam pair to use.

However, in this example, when the base station determines whether aresponse message was received, base station 1401 determines that no ACKwas received, i.e., the response message is unreceived. Therefore, thebeam set on which UE 1403 will be communicating after the switch time isunknown to base station 1401, and this situation is represented in FIG.14 by an unknown beam set 1414 on which UE 1403 is communicating afterswitch time 1411. Even though base station 1401 does not know whether UE1403 will switch beams, base station 1401 performs a beam switch 1415 tosecond beam set 1409 at switch time 1411.

The base station 1401 can then transmit a signal 1417 to UE 1403 viasecond beam set 1409 after performing beam switch 1415. In variousembodiments, signal 1417 can be, for example, a request for a responsethat UE 1403 is communicating via second beam set 1409. In variousembodiments, signal 1417 can be, for example, merely the continuation ofnormal communications between base station 1401 and UE 1403 (e.g.,control and data signals). In this regard, base station 1401 may monitorfor an ACK in response to signal 1417, may monitor for normalcommunication in response to signal 1417, etc. In some embodiments, basestation might not transmit a signal, such a signal 1417, after switchingbeams, but may simply switch beams and then await communication from UE1403 via the second beam set.

In the example of FIG. 14, base station 1401 monitors for an ACK tosignal 1417. If UE 1403 had received BSM 1407 and had switched tocommunication via second beam set 1409, then UE 1403 can send an ACK1419 to base station 1401. In this case, base station 1401 can receiveACK 1419 and can continue communication with UE 1403 via second beam set1409. In other words, the unknown beam set 1414 is now known to besecond beam set 1409, and the remaining beam switches, signals, andpotential ACKs shown in FIG. 14 can be disregarded.

However, if UE 1403 did not receive BSM 1407 and did not switch tosecond beam set 1409, UE 1403 would not have switched to the second beamset and, therefore, would not receive signal 1417 from base station1401. In this case, UE 1403 would not transmit ACK 1419. Because ACK1419 may or may not be transmitted, ACK 1419 is shown as a dashed arrow.This dashed arrow representation will be used herein for other signalsthat may or may not be transmitted.

If base station 1401 does not receive ACK 1419, base station 1401 canperform a beam switch 1421 to switch communication back to first beamset 1405. In other words, if UE 1403 is not communicating via secondbeam set 1409 after switch time 1411, base station 1401 can assume thatUE 1403 did not receive BSM 1407 and is, therefore, still communicatingvia first beam set 1405. After beam switch 1421, base station 1401 cantransmit a signal 1423 to UE 1403 via first beam set 1405 and monitorfor an ACK. UE 1403 may or may not transmit an ACK 1425. If base station1401 receives ACK 1425, base station 1401 and UE 1403 can continuecommunication, as described above, on first beam set 1405 (i.e., theunknown beam set 1414 is now know to be first beam set 1405). However,if base station 1401 does not receive ACK 1425, base station 1401 canrepeat the switching back and forth between the first and second beamsets, e.g., by performing a beam switch 1427, transmitting a signal1429, and monitoring for an ACK 1431.

It should be noted that in some embodiments, base station 1401 might nottransmit signal 1423 after switching back to first beam set 1405,because the probability can be high that UE 1403 did not switch beamsand is, therefore, communicating on the first beam set. Thus, it may bemore efficient for base station 1401 to simply continue normalcommunications when switching back to the first beam set afterdetermining that UE 1403 did not switch beams.

FIGS. 15 and 16 illustrate the example shown in FIG. 14 in two differentsignaling error situations.

FIG. 15 illustrates an implementation of FIG. 14 in a situation that aresponse to a BSM is lost. Initially, a base station 1501 and a UE 1503can be communicating via a first beam set 1505 using, for example, mmWcommunications. The base station 1501 can transmit a BSM 1507 includingan instruction to switch to communication via a second beam set 1509 ata switch time 1511. The base station 1501 may expect a response message,e.g., an ACK, from UE 1503 at an expected ACK time 1513 and, therefore,may be monitoring for a response indicating receipt of BSM 1507. In thisexample, UE 1503 receives BSM 1507 and transmits a response message,e.g., ACK 1525. The UE 1503 prepares to switch to communication viasecond beam set 1509 at switch time 1511.

However, in this example, ACK 1525 is lost, e.g., is not received bybase station 1501. Therefore, base station 1501 determines that no ACKwas received, i.e., the response message is unreceived. Therefore, thebeam set on which UE 1503 will be communicating after the switch time isunknown to base station 1501. Even though base station 1501 does notknow whether UE 1503 will switch beams, base station 1501 performs abeam switch 1515 to second beam set 1509 at switch time 1511.

The base station 1501 can then transmit a signal 1517 to UE 1503 viasecond beam set 1509 after performing beam switch 1515. In this example,signal 1517 can be a request for a response that UE 1503 iscommunicating via second beam set 1509. Base station 1501 can monitorfor an ACK to signal 1517. As described above with respect to FIG. 14,if the base station does not receive an ACK to the signal sent on thesecond beam set, the base station can switch back to communication viathe first beam set and attempt to communicate with the UE. In theexample of FIG. 15, base station 1501 remains on second beam set 1509for a time period 1518 during which an ACK should be received from UE1503. In other words, base station 1501 can set time period 1518 as anamount of time to remain on second beam set 1509 in order to determineif UE 1503 is communicating via the second beam set. In this case, timeperiod 1518 can be am amount of time required for an ACK to be receivedfrom UE 1503. In various embodiments, time period 1518 can be set inother ways. For example, the base station may send multiple ACK requestsand set the time period to begin at the time of sending the first ACKrequest and to end at a time after an ACK to the last ACK request isexpected to be received. In various embodiments, the base station mightnot send an ACK request, but may simply attempt normal communication viathe second beam set, and may set the time period based on, e.g., aconfidence determination that normal communication would be establishedwithin a particular time period if the UE is communicating via thesecond beam set. For example, the time period may be set based on a SNRof the environment, e.g., a shorter time period may set in a high-SNRenvironment and a longer time period may be set in a low-SNRenvironment.

In this example, because UE 1503 received BSM 1507 and switched tocommunication via second beam set 1509, then UE 1503 receives signal1517 and sends an ACK 1519 to base station 1501. In this case, basestation 1501 can receive ACK 1519 and can continue communication with UE1503 via second beam set 1509.

FIG. 16 illustrates an implementation of FIG. 14 in a situation that aBSM is lost. Initially, a base station 1601 and a UE 1603 can becommunicating via a first beam set 1605 using, for example, mmWcommunications. The base station 1601 can transmit a BSM 1607 includingan instruction to switch to communication via a second beam set 1609 ata switch time 1611. The base station 1601 may expect a response message,e.g., an ACK, from UE 1603 at an expected ACK time 1613 and, therefore,may be monitoring for a response indicating receipt of BSM 1607. In thisexample, BSM 1607 is lost, e.g., not received by UE 1603. Therefore, UE1603 does not transmit a response message and does not prepare to switchto communication via second beam set 1609 at switch time 1611. Instead,UE 1603 continues to communicate via first beam set 1605 after switchtime 1611.

Base station 1601 determines that no ACK was received, i.e., theresponse message is unreceived. Therefore, the beam set on which UE 1603will be communicating after the switch time is unknown to base station1601. Even though base station 1601 does not know whether UE 1603 willswitch beams, base station 1601 performs a beam switch 1615 to secondbeam set 1609 at switch time 1611.

Base station 1601 can then transmit a signal 1617 to UE 1603 via secondbeam set 1609 after performing beam switch 1615. In this example, signal1617 can be a request for a response that UE 1603 is communicating viasecond beam set 1609. Base station 1601 can monitor for an ACK to signal1617 and can remain on second beam set 1609 for a time period 1618during which an ACK should be received from UE 1603. For example, basestation 1601 can set time period 1618 as described above for time period1518 of FIG. 15.

In this example, because UE 1603 did not receive BSM 1607 and did notswitch to communication via second beam set 1609, UE 1603 does not sendan ACK to base station 1601. In this case, base station 1601 can waituntil time period 1618 ends and then can perform a beam switch 1621 toswitch back to communication via first beam set 1605. Base station 1601can then transmit a signal 1623 to UE 1603 via first beam set 1605 afterperforming beam switch 1621. In this example, signal 1623 can be arequest for a response that UE 1603 is communicating via first beam set1605. Base station 1601 can monitor for an ACK to signal 1623 and canremain on first beam set 1605 for a time period 1624 during which an ACKshould be received from UE 1603. For example, base station 1601 can settime period 1624 as described above for time period 1518 of FIG. 15. Inthis example, UE 1603 receives signal 1623 and sends an ACK 1625 to basestation 1601. In this case, base station 1601 can receive ACK 1525 andcan continue communication with UE 1603 via first beam set 1505.

Accordingly, FIGS. 14-16 illustrate examples of beam switch methods thatmay be implemented after a switch time to recover from potential beammisalignment, including switching to a target beam set when a responseto a BSM is unreceived and communicating via the target beam set for atime period during which communication is expected to be established.

FIG. 17 illustrates another example implementation of a method ofwireless communication in accordance with various embodiments. A basestation 1701 and a UE 1703 can be communicating via a first beam set1705 using, for example, mmW communications. The base station 1701 andUE 1703 may, for example, correspond to base station 562 and UE 566 inFIG. 5 above, and base station 1701 may transmit various DL signals andchannels to UE 1703 via first beam set 1705, such as beam or beams 510.UE 1703 may transmit various UL signals and channels to base station1701 via first beam set 1705, such as beam or beams 520 (which areassociated with beam or beams 510 in first beam pair 550, e.g., firstbeam set 1705).

The base station 1701 can transmit a BSM 1707 including an instructionto switch to communication via a second beam set 1709 at a switch time1711. The BSM 1707 may include information of a beam identifier forsecond beam set 1709, also referred to as the target beam, which couldbe, e.g., second beam pair 552. In some examples, BSM 1707 may notinclude a beam identifier. In some examples, BSM 1707 may be transmittedas part of a MAC or RRC message. The base station 1701 may expect aresponse message, e.g., an ACK, from UE 1703 at an expected ACK time1713 and, therefore, may be monitoring for a response indicating receiptof BSM 1707. UE 1703 may include the target beam (second beam set)identifiers in the UL transmission to echo back the target beamidentifiers. In one aspect, UE 1703 may generate a sequence from thetarget beam identifiers, and include the sequence in the ULtransmission. The base station 1701 may determine and confirm the targetbeam pair from the sequence in the UL transmission. In some examples,both the source beam pair (first beam set) and the target beam pair maybe of sufficient quality for communication, the mechanism may help basestation 1701 to determine which of the source beam pair and the targetbeam pair to use.

However, in this example, when the base station determines whether aresponse message was received, base station 1701 determines that no ACKwas received, i.e., the response message is unreceived. Therefore, thebeam set on which UE 1703 will be communicating after the switch time isunknown to base station 1701, and this situation is represented in FIG.17 by an unknown beam set 1714 on which UE 1703 is communicating afterswitch time 1711. Even though base station 1701 does not know whether UE1703 will switch beams, base station 1701 performs a beam switch 1715 tosecond beam set 1709 at switch time 1711.

The base station 1701 can then transmit a signal 1717 to UE 1703 viasecond beam set 1709 after performing beam switch 1715. In variousembodiments, signal 1717 can be, for example, a request for a responsethat UE 1703 is communicating via second beam set 1709.

However, unlike the example of FIG. 14 above, base station 1701 does notcontinuously maintain communication via second beam set 1709 to monitorfor an ACK in response to signal 1717. Instead, base station 1701performs a beam switch 1719 to switch to first beam set 1705, transmitsa signal 1721 to UE 1703 via first beam set 1705, and performs a beamswitch 1723 to switch back to second beam set 1709 before an expectedACK time for receiving a possible ACK 1725 to signal 1717. In otherwords, in this example there is enough time in between transmission ofsignal 1717 and the expected ACK time of ACK 1725 in response to signal1717, that base station 1701 can switch to the first beam set, sendanother signal, and switch back to the second beam set to monitor forACK 1725. In this way, for example, base station 1701 may recover frombeam misalignment more quickly. More specifically, by transmittingsignal 1721 on the first beam set during the time the base station iswaiting for ACK 1725, a response to signal 1721 can be received sooner(because the base station does not have to wait to determine if ACK 1725was received before switching to first beam set 1705 and transmittingsignal 1721). Thus, base station 1701 can determine sooner if UE 1703did not switch beams.

After base station 1701 switches back to second beam set 1709 at beamswitch 1723, base station 1701 monitors for ACK 1725. If base station1701 receives ACK 1725, communication with UE 1703 can continue viasecond beam set 1709. In other words, unknown beam set 1714 can becomesecond beam set 1709, and the remaining beam switches, signals, andpotential ACKs shown in FIG. 17 can be disregarded.

If base station 1701 does not receive ACK 1725, base station 1701 canperform a beam switch 1727 to switch to communication via first beam set1705 and monitor for an ACK 1729 in response to signal 1721. If basestation 1701 receives ACK 1729, communication with UE 1703 can continuevia first beam set 1705. In other words, unknown beam set 1714 canbecome first beam set 1705, and the remaining beam switches, signals,and potential ACKs shown in FIG. 17 can be disregarded. If base station1701 does not receive ACK 1729, base station can continue switching backand forth between the first and second beam sets with beam switches1731, 1733, 1735, and 1737, sending signals 1739 and 1741, andmonitoring for potential ACKs 1743 and 1745 as shown in FIG. 17. Ofcourse, base station 1701 might change the recovery method, for example,after a time period, after a number of failed attempts, etc. Forexample, after 6 failed attempts at receiving an ACK, base station 1701may switch to using a method similar to the one described with respectto FIG. 14 above, or may switch to another recovery method.

It should be noted that in some embodiments, base station 1701 might nottransmit signal 1721 after switching back to first beam set 1705,because the probability can be high that UE 1703 did not switch beamsand is, therefore, communicating on the first beam set. Thus, it may bemore efficient for base station 1701 to simply continue normalcommunications when switching back to the first beam set afterdetermining that UE 1703 did not switch beams.

Accordingly, FIG. 17 illustrates an example beam switch method that maybe implemented after a switch time to recover from potential beammisalignment, including performing multiple switches between a targetbeam set and a source beam set in the event that a response to a BSM isunreceived, where some of the beam switches are performed between a timeof sending a signal and an expected time of response to the signal.

FIG. 18 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments. Initially, a basestation 1801 and a UE 1803 can be communicating via a first beam set1805 using, for example, mmW communications. The base station 1801 andUE 1803 may, for example, correspond to base station 562 and UE 566 inFIG. 5 above, and base station 1801 may transmit various DL signals andchannels to UE 1803 via first beam set 1805, such as beam or beams 510.UE 1803 may transmit various UL signals and channels to base station1801 via first beam set 1805, such as beam or beams 520 (which areassociated with beam or beams 510 in first beam pair 550, e.g., firstbeam set 1805).

The base station 1801 can transmit a BSM 1807 including an instructionto switch to communication via a second beam set 1809 at a switch time1811. The BSM 1807 may include information of a beam identifier forsecond beam set 1809, also referred to as the target beam, which couldbe, e.g., second beam pair 552. In some examples, BSM 1807 may notinclude a beam identifier. In some examples, BSM 1807 may be transmittedas part of a MAC or RRC message. The base station 1801 may expect aresponse message, e.g., an ACK, from UE 1803 at an expected ACK time1813 and, therefore, may be monitoring for a response indicating receiptof BSM 1807. UE 1803 may include the target beam (second beam set)identifiers in the UL transmission to echo back the target beamidentifiers. In one aspect, UE 1803 may generate a sequence from thetarget beam identifiers, and include the sequence in the ULtransmission. The base station 1801 may determine and confirm the targetbeam pair from the sequence in the UL transmission. In some examples,both the source beam pair (first beam set) and the target beam pair maybe of sufficient quality for communication, the mechanism may help basestation 1801 to determine which of the source beam pair and the targetbeam pair to use.

However, in this example, when the base station determines whether aresponse message was received, base station 1801 determines that no ACKwas received, i.e., the response message is unreceived. Therefore, thebeam set on which UE 1803 will be communicating after the switch time isunknown to base station 1801, and this situation is represented in FIG.18 by an unknown beam set 1814 on which UE 1803 is communicating afterswitch time 1811. The base station 1801 can determine whether to switchto second beam set 1809 at switch time 1811. In this example, basestation 1801 determines not to switch to second beam set 1809 at switchtime 1811. Therefore, at switch time 1811, base station 1801 continuescommunication via first beam set 1805. The base station 1801 can send asignal 1817 via first beam set 1805. In this example, signal 1817 can bea request for a response that UE 1803 is communicating via first beamset 1805. In this case, base station 1801 may be expecting to receive aresponse message, and can monitor for an ACK. In various embodiments,signal 1817 can be normal communication (e.g., data signals, controlsignals, etc.) with UE 1803, and base station 1801 can simply determineif UE 1803 is communicating via first beam set 1805 based on receivingcommunications from UE 1803 via the first beam set. In some embodiments,base station might not transmit a signal, such a signal 1817, afterswitch time 1811, but may await communication from UE 1803 via the firstbeam set.

In the example of FIG. 18, base station 1801 monitors for an ACK tosignal 1817. If UE 1803 had not received BSM 1807 and had not switchedbeams, then UE 1803 can send an ACK 1819 to base station 1801 via firstbeam set 1805. In this case, base station 1801 can receive ACK 1819 andcan continue communication with UE 1803 via first beam set 1805. Inother words, the unknown beam set 1814 is now known to be first beam set1805, and the remaining beam switches, signals, and potential ACKs shownin FIG. 18 can be disregarded.

However, if UE 1803 did receive BSM 1807 and switched to second beam set1809 at switch time 1811, UE 1803 would not have received signal 1817from base station 1801. In this case, UE 1803 would not transmit ACK1819. Because ACK 1819 may or may not be transmitted, ACK 1819 is shownas a dashed arrow.

If base station 1801 does not receive ACK 1819, base station 1801 canperform a beam switch 1821 to switch communication to second beam set1809. In other words, if UE 1803 is not communicating via first beam set1805 after switch time 1811, base station 1801 can assume that UE 1803received BSM 1807 and is, therefore, communicating via second beam set1809. After beam switch 1821, base station 1801 can transmit a signal1823 to UE 1803 via second beam set 1809 and monitor for an ACK. UE 1803may or may not transmit an ACK 1825. If base station 1801 receives ACK1825, base station 1801 and UE 1803 can continue communication, asdescribed above, on second beam set 1809 (i.e., the unknown beam set1814 is now know to be second beam set 1809). However, if base station1801 does not receive ACK 1825, base station 1801 can repeat theswitching back and forth between the first and second beam sets, e.g.,by performing a beam switch 1827, transmitting a signal 1829, andmonitoring for an ACK 1831.

It should be noted that in some embodiments, base station 1801 might nottransmit signal 1823 after switching to second beam set 1809, becausethe probability can be high that UE 1803 switched beams and is,therefore, communicating on the second beam set. Thus, it may be moreefficient for base station 1801 to simply continue normal communicationswhen switching to the second beam set after determining that UE 1803 isnot communicating on first beam set 1805.

Accordingly, FIG. 18 illustrates an example beam switch method that maybe implemented after a switch time to recover from potential beammisalignment, including sending a BSM to switch from a source beam setto a target beam set at a switch time, determining that a response tothe BSM is unreceived, and determining whether to perform a beam switchto the target beam set at the switch time or to maintain communicationvia the source beam set at the switch time.

Now turning to FIG. 19, this figure illustrates an example beam switchmethod that may be implemented to avoid signaling errors such asdescribed above. In various embodiments, for example, a method accordingto FIG. 19 can use a fast beam recovery procedure in place of aconventional ACK procedure.

FIG. 19 illustrates an example implementation of a method of wirelesscommunication in accordance with various embodiments. Initially, a basestation 1901 and a UE 1903 can be communicating via a first beam set1905 using, for example, mmW communications. The base station 1901 andUE 1903 may, for example, correspond to base station 562 and UE 566 inFIG. 5 above, and base station 1901 may transmit various DL signals andchannels to UE 1903 via first beam set 1905, such as beam or beams 510.UE 1903 may transmit various UL signals and channels to base station1901 via first beam set 1905, such as beam or beams 520 (which areassociated with beam or beams 510 in first beam pair 550, e.g., firstbeam set 1905).

The base station 1901 can transmit a BSM 1907 including an instructionto switch to communication via a second beam set 1909 at a switch time1911. The BSM 1907 may include information of a beam identifier forsecond beam set 1909, also referred to as the target beam, which couldbe, e.g., second beam pair 552. In some examples, BSM 1907 may notinclude a beam identifier. In some examples, BSM 1907 may be transmittedas part of a MAC or RRC message. The base station 1901 does not expect aresponse message and does not monitor for a response message, and thisis represented in FIG. 19 by a period of time labeled no expected ACK1913, which is the time period between the sending of BSM 1907 andswitch time 1911. Because base station 1901 does not monitor for aresponse, base station 1901 does not know whether UE 1903 received BSM1907. Therefore, the beam set on which UE 1903 will be communicatingafter the switch time is unknown to base station 1901, and thissituation is represented in FIG. 19 by an unknown beam set 1914 on whichUE 1903 is communicating after switch time 1911. The base station 1901performs a beam switch 1915 to second beam set 1909 at switch time 1911.

The base station 1901 can then transmit a signal 1917 to UE 1903 viasecond beam set 1909 after performing beam switch 1915. In variousembodiments, signal 1917 can be, for example, a request for a responsethat UE 1903 is communicating via second beam set 1909. In variousembodiments, signal 1917 can be, for example, merely the continuation ofnormal communications between base station 1901 and UE 1903 (e.g.,control and data signals). In this regard, base station 1901 may monitorfor an ACK in response to signal 1917, may monitor for normalcommunication in response to signal 1917, etc. In some embodiments, basestation might not transmit a signal, such a signal 1917, after switchingbeams, but may simply switch beams and then await communication from UE1903 via the second beam set.

In the example of FIG. 19, base station 1901 monitors for an ACK tosignal 1917. If UE 1903 had received BSM 1907 and had switched tocommunication via second beam set 1909, then UE 1903 can send an ACK1919 to base station 1901. In this case, base station 1901 can receiveACK 1919 and can continue communication with UE 1903 via second beam set1909. In other words, the unknown beam set 1914 is now known to besecond beam set 1909, and the remaining beam switches, signals, andpotential ACKs shown in FIG. 19 can be disregarded.

However, if UE 1903 did not receive BSM 1907 and did not switch tosecond beam set 1909, UE 1903 would not have switched to the second beamset and, therefore, would not receive signal 1917 from base station1901. In this case, UE 1903 would not transmit ACK 1919. Because ACK1919 may or may not be transmitted, ACK 1919 is shown as a dashed arrow.

If base station 1901 does not receive ACK 1919, base station 1901 canperform a beam switch 1921 to switch communication back to first beamset 1905. In other words, if UE 1903 is not communicating via secondbeam set 1909 after switch time 1911, base station 1901 can assume thatUE 1903 did not receive BSM 1907 and is, therefore, still communicatingvia first beam set 1905. After beam switch 1921, base station 1901 cantransmit a signal 1923 to UE 1903 via first beam set 1905 and monitorfor an ACK. UE 1903 may or may not transmit an ACK 1925. If base station1901 receives ACK 1925, base station 1901 and UE 1903 can continuecommunication, as described above, on first beam set 1905 (i.e., theunknown beam set 1914 is now know to be first beam set 1905). However,if base station 1901 does not receive ACK 1925, base station 1901 canrepeat the switching back and forth between the first and second beamsets, e.g., by performing a beam switch 1927, transmitting a signal1929, and monitoring for an ACK 1931.

It should be noted that in some embodiments, base station 1901 might nottransmit signal 1923 after switching back to first beam set 1905,because the probability can be high that UE 1903 did not switch beamsand is, therefore, communicating on the first beam set. Thus, it may bemore efficient for base station 1901 to simply continue normalcommunications when switching back to the first beam set afterdetermining that UE 1903 did not switch beams. Furthermore, although theprocess performed after beam switch 1915 in FIG. 19 is similar to theprocess performed with respect to the example of FIG. 14, it should beunderstood that any of the forgoing methods of beam recovery after aplanned beam switch could be implemented in the example of FIG. 19. Forexample, in some embodiments, after beam switch 1915, base station 1901could perform a recovery process similar to the example of FIG. 17 toquickly switch between beam sets. In some embodiments, base station 1901could determine a likelihood of delivery failure of BSM 1907 anddetermine if beam switch 1915 should be performed or if base station1901 should continue to communicate via first beam set 1905, similar tothe approach of FIG. 18. Other forms of beam recovery could beimplemented, and various combinations could be implemented, in theexample of FIG. 19.

FIG. 20 is a flowchart 2000 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can transmit (2001) a BSM to a second device via a firstbeam set (such as a source beam set, also referred to simply as a sourcebeam), the BSM including a command to switch from communication via thefirst beam set to communication via a second beam set (such as a targetbeam set, also referred to simply as a target beam) at a switch time.Referring to FIG. 6, for example, base station 601 can send BSM 607 toUE 603 via first beam set 605. The first device can receive (2002) aresponse message from the second device via the first beam set, theresponse message indicating that the second device received the BSM. Forexample, the first device can monitor for an acknowledgement message viathe source beam and can determine whether an acknowledgement message isreceived. For example, base station 601 can monitor for ACK 615 atexpected ACK time 613. The first device can send (2003), to the seconddevice, a communication via the second beam set after the switch time ifthe response message is received.

FIG. 21 is a flowchart 2100 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can monitor (2101) for a BSM from a second device via afirst beam set, the BSM including a command to switch from communicationvia the first beam set to communication via a second beam set at aswitch time. Referring to FIG. 6, for example, UE 603 can monitor forBSM 607 to from base station 601 via first beam set 605. The firstdevice can send (2102) send a response message to the second device whenthe BSM is received. For example, UE 603 can send ACK 615 at expectedACK time 613. The first device can switch (2103) switch fromcommunication via the first beam set to communication via the secondbeam set at the switch time. For example, UE 603 can perform beam switch617.

FIG. 22 is a flowchart 2200 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can transmit (2201) a first BSM to a second device. Thefirst BSM can include a first instruction for switching beams. Referringto FIG. 11A, for example, base station 1101 can transmit BSM 1105 to UE1103, and the BSM can instruct the UE to execute planned beam switch1107 at a particular switch time. The first device can monitor (2202)for an ACK from the second device, the ACK acknowledging receipt of theBSM. For example, base station 1101 monitors for an ACK at expected ACKtime 1109. The first device can determine (2203) if an ACK is received.If an ACK is received, the first device can switch beams (2204) inaccordance with the BSM that the ACK is in response to, which in thiscase is the first BSM.

However, if the first device determines at 2203 that an ACK was notreceived, the first device can select a reset state from a plurality ofreset states including a first state for the second device to disregardthe first instruction and a second state for the second device tomaintain execution of the first instruction. For example, the firstdevice can select (2205) a reset state of 1, which can indicate that thesecond device should disregard the beam switch instruction of the firstBSM. The first device can also advance (2206) the switch time to a latertime, which can allow the beam switch to occur after the first devicereceives an ACK from the second device, for example. The first devicecan transmit a second BSM to the second device before the second devicecompletes execution of the first instruction. The second BSM can includea second instruction for switching beams and can indicate which of thereset states is selected. For example, the first device can transmit(2207) the second BSM indicating a reset state of 1 and indicating theadvanced switch time. Referring to FIG. 11B, for example, base station1101 can transmit BSM 1113, which indicates to disregard planned beamswitch 1107 and to execute new beam switch 1115 at the later time shownin the figure. Base station 1101 can transmit BSM 1113 before the timethat planned beam switch 1107 is scheduled to be executed, which isshown as subframe 9 in FIG. 11A. Therefore, BSM 1113 is transmittedbefore UE 1103 completes execution of the first instruction, i.e., thebeam switch instruction in BSM 1105.

The first device can again monitor (2208) for an ACK and determine(2209) whether an ACK is received. If an ACK to the second BSM isreceived, the first device can switch beams (2204) in accordance withthe BSM that the ACK is in response to, which in this case is the secondBSM. However, if the first device determines at 2209 that an ACK was notreceived, the first device can determine (2210) whether a maximum numberof attempts at beam recovery have been performed. In other words, thefirst device might limit the number of attempts of sending BSMs withreset of 1 and advanced switch time. For example, the first device mighttry sending a maximum of 10 such BSMs. If the first device determines at2210 that the maximum number of attempts has been tried, the firstdevice can attempt (2211) an alternative recovery procedure. However, ifthe first device determines at 2210 that the maximum number of attemptshas not been tried, the process can proceed to 2205 to repeat selecting(2205) the reset state of 1, advancing (2206) the switch time,transmitting (2207) the BSM, monitoring (2208) for an ACK, anddetermining (2209) whether an ACK is received. For example, as shown inFIGS. 11B-C, base station 1101 can transmit BSM 1123 after failing toreceive an ACK from UE 1103 at expected ACK time 1119.

FIG. 23 is a flowchart 2300 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can receive (2301) a first BSM from a second device andcan send (2302) an acknowledgement message. The first BSM can include afirst instruction for switching beams. Referring to FIG. 10A, forexample, UE 1003 can receive BSM 1005 from base station 1001 and cansend ACK 1009 to base station 1001. The first device can receive (2303)a second BSM from the second device, the second BSM including a secondinstruction for switching beams and indicating a reset state associatedwith the first BSM. Referring to FIGS. 10B-C, for example, UE 1003 canreceive a second BSM, i.e., BSM 1011 (indicating a first reset state,which is to disregard the beam switch instruction of BSM 1005) or BSM1019 (indicating a second reset state, which is to maintain execution ofthe beam switch instruction of BSM 1005). The first device can send(2304) an acknowledgement message. In FIGS. 10B-C, for example, UE 1003can send ACK 1015 or ACK 1023.

The first device can determine whether to disregard the firstinstruction or to maintain execution of the first instruction based onthe indicated reset state. For example, the first device can determine(2305) which selected reset state the second BSM indicates. In FIG. 10B,for example, UE 1003 determines that BSM 1011 indicates the first resetstate, e.g., reset state=1. On the other hand, in FIG. 10C, UE 1003determines that BSM 1019 indicates the second reset state, e.g., resetstate=0. If the indicated reset state is 1, for example, the firstdevice can disregard (2306) the beam switch instruction of the first BSMand can switch beams according to the beam switch instruction of thesecond BSM. In FIG. 10B, for example, UE 1003 disregards planned beamswitch 1007 (i.e., disregarded beam switch 1017) and executes only newbeam switch 1013. On the other hand, if the indicated reset state is 0,for example, the first device can switch beams (2307) according to theinstructions of the first and second BSMs. In FIG. 10C, for example, UE1003 executes both planned beam switch 1007 and added beam switch 1021.

FIG. 24 is a flowchart 2400 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can transmit (2401) a BSM to a second device via a firstbeam set (such as a source beam set, also referred to simply as a sourcebeam), the BSM including a command to switch from communication via thefirst beam set to communication via a second beam set (such as a targetbeam set, also referred to simply as a target beam) at a switch time.Referring to FIG. 14, for example, base station 1401 can send BSM 1407to UE 1403 via first beam set 1405. The first device can determinewhether a response message is received from the second device via thefirst beam set, the response message indicating that the second devicereceived the BSM. For example, the first device can monitor (2402) foran acknowledgement message via the source beam and can determine (2403)whether an acknowledgement message is received. For example, basestation 1401 can monitor for a ACK at expected ACK time 1413. If aresponse message, such as an ACK, is received the first device canswitch (2404) beams to the target beam at the switch time and cancontinue (2405) to communicate with the second device.

If a response message is unreceived, the first device can still switch(2406) beams to the target beam at the switch time. For example, basestation 1401 can execute beam switch 1415 at switch time 1411 to switchto communication via second beam set 1409. The first device can thensend, to the second device, a communication via the target beam afterthe switch time. For example, the first device can send (2407) an ACKrequest to the second device via the target beam. In FIG. 14, forexample, base station 1401 can send signal 1417 via second beam set1409. The first device can monitor (2408) for an ACK via the target beamand, if an ACK is received can continue (2405) communications with thesecond device via the target beam. On the other hand, if an ACK is notreceived via the target beam, the first device can determine (2409)whether a maximum number of attempts at beam recovery have beenperformed. In other words, the first device might limit the number ofattempts of switching beams and sending ACK requests. For example, thefirst device might try switching beams a maximum of 10 times. If thefirst device determines at 2409 that the maximum number of attempts hasbeen tried, the first device can attempt (2410) an alternative recoveryprocedure. However, if the first device determines at 2409 that themaximum number of attempts has not been tried, the first device canswitch beams (2411) to the source beam and can send (2412) an ACKrequest via the source beam, and the process can proceed to 2402 tomonitor for an ACK. For example, base station 1401 can execute beamswitch 1421 to switch back to first beam set 1405 and can send signal1423 via the first beam set. In this way, for example, the first devicecan simply proceed with the planned beam switch even though an ACK tothe BSM is unreceived, which may potentially avoid time-consuming beamrecovery procedures.

FIG. 25 is a flowchart 2500 illustrating an example method of wirelesscommunication via multiple beams in accordance with various embodiments.A first device can monitor (2501) for a BSM from a second device via afirst beam set, the BSM including a command to switch from communicationvia the first beam set to communication via a second beam set at aswitch time. The first device can send (2502) a response message to thesecond device when the BSM is received and can monitor (2503) for asecond communication from the second device via the first beam set whenthe BSM is unreceived. The second communication via the first beam setcan be monitored at a second time subsequent to a first time in which afirst communication is sent to the first device via the second beam set.Referring to FIGS. 15 and 16, for example, UE 1503 and UE 1603 canmonitor for BSMs. FIG. 15 illustrates when BSM 1507 is received, UE 1503can send a response message, i.e., ACK 1525. On the other hand, FIG. 16illustrates when BSM 1607 is unreceived, UE 1603 can monitor for asecond communication, i.e., signal 1623, at a time subsequent to thetime a first communication, i.e., signal 1617, is sent via second beamset 1609.

FIG. 26 is a conceptual data flow diagram 2600 illustrating the dataflow between different means/components in an exemplary apparatus 2602.The apparatus may be a base station, for example. The apparatus includesa receiver 2604 that receives signals, a controller 2606 that controlsvarious functions of apparatus 2602, a response monitor 2608 thatmonitors for a response, and a transmitter 2610 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 2650 via first and second beam pairs. Apparatus 2650 can be aUE, for example. Response monitor 2608 can, for example, determinewhether a response message is received from apparatus 2650 via a firstbeam set, the response message indicating that apparatus 2650 received aBSM sent by apparatus 2602. Transmitter 2610 can, for example, send toapparatus 2650, a communication via a second beam set after a switchtime when the response message is received.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 20. Assuch, each block in the aforementioned flowchart of FIG. 20 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 27 is a diagram 2700 illustrating an example of a hardwareimplementation for an apparatus 2602′ employing a processing system2714. The processing system 2714 may be implemented with a busarchitecture, represented generally by the bus 2724. The bus 2724 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 2714 and the overalldesign constraints. The bus 2724 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 2704, the components 2604, 2606, 2608, 2610, and thecomputer-readable medium/memory 2706. The bus 2724 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 2714 may be coupled to a transceiver 2710. Thetransceiver 2710 is coupled to one or more antennas 2720. Thetransceiver 2710 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2710 receives asignal from the one or more antennas 2720, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2714, specifically the receiver 2604. In addition, thetransceiver 2710 receives information from the processing system 2714,specifically the transmitter 2610, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 2720. The processing system 2714 includes a processor 2704coupled to a computer-readable medium/memory 2706. The processor 2704 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2706. The software, whenexecuted by the processor 2704, causes the processing system 2714 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2706 may also be used forstoring data that is manipulated by the processor 2704 when executingsoftware. The processing system 2714 further includes at least one ofthe components 2604, 2606, 2608, 2610. The components may be softwarecomponents running in the processor 2704, resident/stored in thecomputer readable medium/memory 2706, one or more hardware componentscoupled to the processor 2704, or some combination thereof. Theprocessing system 2714 may be a component of the base station 310 andmay include the memory 376 and/or at least one of the TX processor 316,the RX processor 370, and the controller/processor 375.

In one configuration, the apparatus 2602/2602′ for wirelesscommunication includes means for transmitting a BSM to a second devicevia a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time, means for receiving a response message from thesecond device via the first beam set, the response message indicatingthat the second device received the BSM, and means for sending, to thesecond device, a communication via the second beam set after the switchtime if the response message is received. The aforementioned means maybe one or more of the aforementioned components of the apparatus 2602and/or the processing system 2714 of the apparatus 2602′ configured toperform the functions recited by the aforementioned means. As describedsupra, the processing system 2714 may include the TX Processor 316, theRX Processor 370, and the controller/processor 375. As such, in oneconfiguration, the aforementioned means may be the TX Processor 316, theRX Processor 370, and the controller/processor 375 configured to performthe functions recited by the aforementioned means.

FIG. 28 is a conceptual data flow diagram 2800 illustrating the dataflow between different means/components in an exemplary apparatus 2802.The apparatus may be a UE, for example. The apparatus includes areceiver 2804 that receives signals, a controller 2806 that controlsvarious functions of apparatus 2802, a response monitor 2808 thatmonitors for a response, and a transmitter 2810 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 2850 via first and second beam pairs. Apparatus 2850 can be abase station, for example. Response monitor 2808 can, for example,monitor for a BSM from apparatus 2850 via a first beam set, the BSMincluding a command to switch from communication via the first beam setto communication via a second beam set at a switch time, can send aresponse message to apparatus 2850 via the first beam set when the BSMis received, and can switch from communication via the first beam set tocommunication via the second beam set at the switch time.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 21. Assuch, each block in the aforementioned flowchart of FIG. 21 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 29 is a diagram 2900 illustrating an example of a hardwareimplementation for an apparatus 2802′ employing a processing system2914. The processing system 2914 may be implemented with a busarchitecture, represented generally by the bus 2924. The bus 2924 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 2914 and the overalldesign constraints. The bus 2924 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 2904, the components 2804, 2806, 2808, 2810, and thecomputer-readable medium/memory 2906. The bus 2924 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 2914 may be coupled to a transceiver 2910. Thetransceiver 2910 is coupled to one or more antennas 2920. Thetransceiver 2910 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2910 receives asignal from the one or more antennas 2920, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2914, specifically the receiver 2804. In addition, thetransceiver 2910 receives information from the processing system 2914,specifically the transmitter 2810, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 2920. The processing system 2914 includes a processor 2904coupled to a computer-readable medium/memory 2906. The processor 2904 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2906. The software, whenexecuted by the processor 2904, causes the processing system 2914 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2906 may also be used forstoring data that is manipulated by the processor 2904 when executingsoftware. The processing system 2914 further includes at least one ofthe components 2804, 2806, 2808, 2810. The components may be softwarecomponents running in the processor 2904, resident/stored in thecomputer readable medium/memory 2906, one or more hardware componentscoupled to the processor 2904, or some combination thereof. Theprocessing system 2914 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356,

In one configuration, the apparatus 2802/2802′ for wirelesscommunication includes means for monitoring for a BSM from a seconddevice via a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time, means for sending a response message to the seconddevice when the BSM is received, and means for switching fromcommunication via the first beam set to communication via the secondbeam set at the switch time. The aforementioned means may be one or moreof the aforementioned components of the apparatus 2802 and/or theprocessing system 2914 of the apparatus 2802′ configured to perform thefunctions recited by the aforementioned means. As described supra, theprocessing system 2914 may include the TX Processor 368, the RXProcessor 356, and the controller/processor 359. As such, in oneconfiguration, the aforementioned means may be the TX Processor 368, theRX Processor 356, and the controller/processor 359 configured to performthe functions recited by the aforementioned means.

FIG. 30 is a conceptual data flow diagram 3000 illustrating the dataflow between different means/components in an exemplary apparatus 3002.The apparatus may be a base station, for example. The apparatus includesa receiver 3004 that receives signals, a controller 3006 that controlsvarious functions of apparatus 3002, a reset state selector 3008 thatselects a reset state, and a transmitter 3010 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 3050 via first and second beam pairs. Apparatus 3050 can be aUE, for example. Reset state selector 3008 can, for example, select areset state from a plurality of reset states including a first stateindicating to disregard a first beam switch instruction and a secondstate to maintain execution of the first instruction.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 22. Assuch, each block in the aforementioned flowchart of FIG. 22 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 31 is a diagram 3100 illustrating an example of a hardwareimplementation for an apparatus 3002′ employing a processing system3114. The processing system 3114 may be implemented with a busarchitecture, represented generally by the bus 3124. The bus 3124 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 3114 and the overalldesign constraints. The bus 3124 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 3104, the components 3004, 3006, 3008, 3010, and thecomputer-readable medium/memory 3106. The bus 3124 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 3114 may be coupled to a transceiver 3110. Thetransceiver 3110 is coupled to one or more antennas 3120. Thetransceiver 3110 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 3110 receives asignal from the one or more antennas 3120, extracts information from thereceived signal, and provides the extracted information to theprocessing system 3114, specifically the receiver 3004. In addition, thetransceiver 3110 receives information from the processing system 3114,specifically the transmitter 3010, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 3120. The processing system 3114 includes a processor 3104coupled to a computer-readable medium/memory 3106. The processor 3104 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 3106. The software, whenexecuted by the processor 3104, causes the processing system 3114 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 3106 may also be used forstoring data that is manipulated by the processor 3104 when executingsoftware. The processing system 3114 further includes at least one ofthe components 3004, 3006, 3008, 3010. The components may be softwarecomponents running in the processor 3104, resident/stored in thecomputer readable medium/memory 3106, one or more hardware componentscoupled to the processor 3104, or some combination thereof. Theprocessing system 3114 may be a component of the base station 310 andmay include the memory 376 and/or at least one of the TX processor 316,the RX processor 370, and the controller/processor 375.

In one configuration, the apparatus 3002/3002′ for wirelesscommunication includes means for transmitting a first BSM to a seconddevice, the first BSM including a first instruction for switching beams,means for selecting a reset state from a plurality of reset statesincluding a first state for the second device to disregard the firstinstruction and a second state for the second device to maintainexecution of the first instruction, and means for transmitting a secondBSM to the second device before the second device completes execution ofthe first instruction, the second BSM including a second instruction forswitching beams and indicating which of the reset states is selected.The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 3002 and/or the processing system 3114 ofthe apparatus 3002′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 3114 mayinclude the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

FIG. 32 is a conceptual data flow diagram 3200 illustrating the dataflow between different means/components in an exemplary apparatus 3202.The apparatus may be a UE, for example. The apparatus includes areceiver 3204 that receives signals, a controller 3206 that controlsvarious functions of apparatus 3202, a reset state determiner 3208 thatdetermines a reset state, and a transmitter 3210 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 3250 via first and second beam pairs. Apparatus 3250 can be abase station, for example. Reset state determiner 3208 can, for example,determine whether to disregard a first beam switch instruction or tomaintain execution of the first beam switch instruction based on anindicated reset state of a BSM.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 23. Assuch, each block in the aforementioned flowchart of FIG. 23 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 33 is a diagram 3300 illustrating an example of a hardwareimplementation for an apparatus 3202′ employing a processing system3314. The processing system 3314 may be implemented with a busarchitecture, represented generally by the bus 3324. The bus 3324 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 3314 and the overalldesign constraints. The bus 3324 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 3304, the components 3204, 3206, 3208, 3210, and thecomputer-readable medium/memory 3306. The bus 3324 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 3314 may be coupled to a transceiver 3310. Thetransceiver 3310 is coupled to one or more antennas 3320. Thetransceiver 3310 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 3310 receives asignal from the one or more antennas 3320, extracts information from thereceived signal, and provides the extracted information to theprocessing system 3314, specifically the receiver 3204. In addition, thetransceiver 3310 receives information from the processing system 3314,specifically the transmitter 3210, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 3320. The processing system 3314 includes a processor 3304coupled to a computer-readable medium/memory 3306. The processor 3304 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 3306. The software, whenexecuted by the processor 3304, causes the processing system 3314 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 3306 may also be used forstoring data that is manipulated by the processor 3304 when executingsoftware. The processing system 3314 further includes at least one ofthe components 3204, 3206, 3208, 3210. The components may be softwarecomponents running in the processor 3304, resident/stored in thecomputer readable medium/memory 3306, one or more hardware componentscoupled to the processor 3304, or some combination thereof. Theprocessing system 3314 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356, and the controller/processor 359.

In one configuration, the apparatus 3202/3202′ for wirelesscommunication includes means for receiving a second BSM from a seconddevice, the second BSM including a second instruction for switchingbeams and indicating a reset state associated with a first BSM includinga first instruction for switching beams, and means for determiningwhether to disregard the first instruction or to maintain execution ofthe first instruction based on the indicated reset state. Theaforementioned means may be one or more of the aforementioned componentsof the apparatus 3202 and/or the processing system 3314 of the apparatus3202′ configured to perform the functions recited by the aforementionedmeans. As described supra, the processing system 3314 may include the TXProcessor 368, the RX Processor 356, and the controller/processor 359.As such, in one configuration, the aforementioned means may be the TXProcessor 368, the RX Processor 356, and the controller/processor 359configured to perform the functions recited by the aforementioned means.

FIG. 34 is a conceptual data flow diagram 3400 illustrating the dataflow between different means/components in an exemplary apparatus 3402.The apparatus may be a base station, for example. The apparatus includesa receiver 3404 that receives signals, a controller 3406 that controlsvarious functions of apparatus 3402, a response monitor 3408 thatmonitors for a response, and a transmitter 3410 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 3450 via first and second beam pairs. Apparatus 3450 can be aUE, for example. Response monitor 3408 can, for example, determinewhether a response message is received from apparatus 3450 via a firstbeam set, the response message indicating that apparatus 3450 received aBSM sent by apparatus 3402. Transmitter 3410 can, for example, send toapparatus 3450, a communication via a second beam set after a switchtime when the response message is unreceived.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 24. Assuch, each block in the aforementioned flowchart of FIG. 24 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 35 is a diagram 3500 illustrating an example of a hardwareimplementation for an apparatus 3402′ employing a processing system3514. The processing system 3514 may be implemented with a busarchitecture, represented generally by the bus 3524. The bus 3524 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 3514 and the overalldesign constraints. The bus 3524 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 3504, the components 3404, 3406, 3408, 3410, and thecomputer-readable medium/memory 3506. The bus 3524 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 3514 may be coupled to a transceiver 3510. Thetransceiver 3510 is coupled to one or more antennas 3520. Thetransceiver 3510 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 3510 receives asignal from the one or more antennas 3520, extracts information from thereceived signal, and provides the extracted information to theprocessing system 3514, specifically the receiver 3404. In addition, thetransceiver 3510 receives information from the processing system 3514,specifically the transmitter 3410, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 3520. The processing system 3514 includes a processor 3504coupled to a computer-readable medium/memory 3506. The processor 3504 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 3506. The software, whenexecuted by the processor 3504, causes the processing system 3514 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 3506 may also be used forstoring data that is manipulated by the processor 3504 when executingsoftware. The processing system 3514 further includes at least one ofthe components 3404, 3406, 3408, 3410. The components may be softwarecomponents running in the processor 3504, resident/stored in thecomputer readable medium/memory 3506, one or more hardware componentscoupled to the processor 3504, or some combination thereof. Theprocessing system 3514 may be a component of the base station 310 andmay include the memory 376 and/or at least one of the TX processor 316,the RX processor 370, and the controller/processor 375.

In one configuration, the apparatus 3402/3402′ for wirelesscommunication includes means for transmitting a BSM to a second devicevia a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time, means for determining whether a response messageis received from the second device via the first beam set, the responsemessage indicating that the second device received the BSM, and meansfor sending, to the second device, a communication via the second beamset after the switch time when the response message is unreceived. Theaforementioned means may be one or more of the aforementioned componentsof the apparatus 3402 and/or the processing system 3514 of the apparatus3402′ configured to perform the functions recited by the aforementionedmeans. As described supra, the processing system 3514 may include the TXProcessor 316, the RX Processor 370, and the controller/processor 375.As such, in one configuration, the aforementioned means may be the TXProcessor 316, the RX Processor 370, and the controller/processor 375configured to perform the functions recited by the aforementioned means.

FIG. 36 is a conceptual data flow diagram 3600 illustrating the dataflow between different means/components in an exemplary apparatus 3602.The apparatus may be a UE, for example. The apparatus includes areceiver 3604 that receives signals, a controller 3606 that controlsvarious functions of apparatus 3602, a response monitor 3608 thatmonitors for a response, and a transmitter 3610 that transmits signals.For example, UL/DL signals can be received from and transmitted to anapparatus 3650 via first and second beam pairs. Apparatus 3650 can be abase station, for example. Response monitor 3608 can, for example,monitor for a BSM from apparatus 3650 via a first beam set, the BSMincluding a command to switch from communication via the first beam setto communication via a second beam set at a switch time, and can monitorfor a second communication from apparatus 3650 via the first beam setwhen the BSM is unreceived, the second communication via the first beamset being monitored at a second time subsequent to a first time in whicha first communication is sent to apparatus 3602 via the second beam set.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 25. Assuch, each block in the aforementioned flowchart of FIG. 25 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 37 is a diagram 3700 illustrating an example of a hardwareimplementation for an apparatus 3602′ employing a processing system3714. The processing system 3714 may be implemented with a busarchitecture, represented generally by the bus 3724. The bus 3724 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 3714 and the overalldesign constraints. The bus 3724 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 3704, the components 3604, 3606, 3608, 3610, and thecomputer-readable medium/memory 3706. The bus 3724 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 3714 may be coupled to a transceiver 3710. Thetransceiver 3710 is coupled to one or more antennas 3720. Thetransceiver 3710 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 3710 receives asignal from the one or more antennas 3720, extracts information from thereceived signal, and provides the extracted information to theprocessing system 3714, specifically the receiver 3604. In addition, thetransceiver 3710 receives information from the processing system 3714,specifically the transmitter 3610, and based on the receivedinformation, generates a signal to be applied to the one or moreantennas 3720. The processing system 3714 includes a processor 3704coupled to a computer-readable medium/memory 3706. The processor 3704 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 3706. The software, whenexecuted by the processor 3704, causes the processing system 3714 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 3706 may also be used forstoring data that is manipulated by the processor 3704 when executingsoftware. The processing system 3714 further includes at least one ofthe components 3604, 3606, 3608, 3610. The components may be softwarecomponents running in the processor 3704, resident/stored in thecomputer readable medium/memory 3706, one or more hardware componentscoupled to the processor 3704, or some combination thereof. Theprocessing system 3714 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356,

In one configuration, the apparatus 3602/3602′ for wirelesscommunication includes means for monitoring for a BSM from a seconddevice via a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time, means for sending a response message to the seconddevice when the BSM is received, and monitoring for a secondcommunication from the second device via the first beam set when the BSMis unreceived, the second communication via the first beam set beingmonitored at a second time subsequent to a first time in which a firstcommunication is sent to the first device via the second beam set. Theaforementioned means may be one or more of the aforementioned componentsof the apparatus 3602 and/or the processing system 3714 of the apparatus3602′ configured to perform the functions recited by the aforementionedmeans. As described supra, the processing system 3714 may include the TXProcessor 368, the RX Processor 356, and the controller/processor 359.As such, in one configuration, the aforementioned means may be the TXProcessor 368, the RX Processor 356, and the controller/processor 359configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication for a firstdevice, comprising: transmitting a beam switch message (BSM) to a seconddevice via a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time; determining whether a response message is receivedfrom the second device via the first beam set, the response messageindicating that the second device received the BSM; and sending, to thesecond device, a communication via the second beam set after the switchtime when the response message is unreceived.
 2. The method of claim 1,wherein the communication is at least one of data, control information,or reference signals.
 3. The method of claim 1, further comprising:determining whether a second response message is received from thesecond device in response to the communication; and maintaining thesecond beam set for communication with the second device upondetermining that the second response message is received.
 4. The methodof claim 3, further comprising: sending, to the second device, a secondcommunication via the first beam set upon determining that the secondresponse message is unreceived; and determining whether a third responsemessage is received from the second device via the first beam set, thethird response message indicating that the second device received thesecond communication.
 5. The method of claim 1, wherein the responsemessage comprises at least one of a reference signal strength indicator(RSSI), reference signal received power (RSRP), reference signalreceived quality (RSRQ), a signal to noise ratio (SNR), a signal tointerference plus noise ratio (SINR), an acknowledgment (ACK), or ameasurement report.
 6. A method of wireless communication for a firstdevice, comprising: monitoring for a beam switch message (BSM) from asecond device via a first beam set, the BSM including a command toswitch from communication via the first beam set to communication via asecond beam set at a switch time; sending a response message to thesecond device when the BSM is received; and monitoring for a secondcommunication from the second device via the first beam set when the BSMis unreceived, the second communication via the first beam set beingmonitored at a second time subsequent to a first time in which a firstcommunication is sent to the first device via the second beam set. 7.The method of claim 6, wherein the first communication is at least oneof data, control information, or reference signals, and the secondcommunication is at least one of data, control information, or referencesignals.
 8. The method of claim 6, wherein the BSM from the seconddevice is unreceived, and the method further comprises: receiving thesecond communication from the second device via the first beam set; andsending a second response message via the first beam set to the seconddevice in response to receiving the second communication.
 9. The methodof claim 6, further comprising: receiving the BSM from the second devicevia the first beam set; switching to the second beam set from the firstbeam set; receiving the first communication from the first device viathe second beam set; and sending a second response message to the seconddevice in response to receiving the first communication.
 10. The methodof claim 6, wherein the response message comprises at least one of areference signal strength indicator (RSSI), reference signal receivedpower (RSRP), reference signal received quality (RSRQ), a signal tonoise ratio (SNR), a signal to interference plus noise ratio (SINR), anacknowledgment (ACK), or a measurement report.
 11. An apparatus forwireless communication, the apparatus being a first device, comprising:a memory; and at least one processor coupled to the memory andconfigured to: transmit a beam switch message (BSM) to a second devicevia a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time; determine whether a response message is receivedfrom the second device via the first beam set, the response messageindicating that the second device received the BSM; and send, to thesecond device, a communication via the second beam set after the switchtime when the response message is unreceived.
 12. The apparatus of claim11, wherein the communication is at least one of data, controlinformation, or reference signals.
 13. The apparatus of claim 11,wherein the at least one processor is further configured to: determinewhether a second response message is received from the second device inresponse to the communication; and maintain the second beam set forcommunication with the second device upon determining that the secondresponse message is received.
 14. The apparatus of claim 13, wherein theat least one processor is further configured to: send, to the seconddevice, a second communication via the first beam set upon determiningthat the second response message is unreceived; and determine whether athird response message is received from the second device via the firstbeam set, the third response message indicating that the second devicereceived the second communication.
 15. The apparatus of claim 11,wherein the response message comprises at least one of a referencesignal strength indicator (RSSI), reference signal received power(RSRP), reference signal received quality (RSRQ), a signal to noiseratio (SNR), a signal to interference plus noise ratio (SINR), anacknowledgment (ACK), or a measurement report.
 16. An apparatus forwireless communication, the apparatus being a first device, comprising:a memory; and at least one processor coupled to the memory andconfigured to: monitor for a beam switch message (BSM) from a seconddevice via a first beam set, the BSM including a command to switch fromcommunication via the first beam set to communication via a second beamset at a switch time; send a response message to the second device whenthe BSM is received; and monitor for a second communication from thesecond device via the first beam set when the BSM is unreceived, thesecond communication via the first beam set being monitored at a secondtime subsequent to a first time in which a first communication is sentto the first device via the second beam set.
 17. The apparatus of claim16, wherein the first communication is at least one of data, controlinformation, or reference signals, and the second communication is atleast one of data, control information, or reference signals.
 18. Theapparatus of claim 16, wherein the BSM from the second device isunreceived, and the at least one processor is further configured to:receive the second communication from the second device via the firstbeam set; and send a second response message via the first beam set tothe second device in response to receiving the second communication. 19.The apparatus of claim 16, wherein the at least one processor is furtherconfigured to: receive the BSM from the second device via the first beamset; switch to the second beam set from the first beam set; receive thefirst communication from the first device via the second beam set; andsend a second response message to the second device in response toreceiving the first communication.
 20. The apparatus of claim 16,wherein the response message comprises at least one of a referencesignal strength indicator (RSSI), reference signal received power(RSRP), reference signal received quality (RSRQ), a signal to noiseratio (SNR), a signal to interference plus noise ratio (SINR), anacknowledgment (ACK), or a measurement report.